The technology disclosed herein relates to a transfer device, a client apparatus, a server apparatus, a reproduction apparatus and a transfer method.
In recent years, a client server system wherein a role which a computer is to play is shared by a client apparatus and a server apparatus is utilized in various scenes. In the client server system, generally a user browses a screen image of the client apparatus and inputs a desired instruction to the client apparatus. Then, the client apparatus transmits a request corresponding to the instruction inputted thereto from the user to the server apparatus. The server apparatus receives the request transmitted from the client apparatus, executes an operation in accordance with the request and sends back a result obtained by the execution as a response to the request to the client apparatus.
Various kinds of information can be transferred between the client apparatus and the server apparatus. For example, a client server system is generally known wherein, if a transmission request for content data is transmitted from the client apparatus to the server apparatus, then content data retained by the server apparatus is transmitted as a response to the transmission request to the client apparatus.
Further, a reproduction apparatus which can reproduce content data has been popularized. In the case where the reproduction apparatus can be connected to the client apparatus, as content data of a reproduction object by the reproduction apparatus, for example, content data which are first transmitted from the server apparatus and received by the client apparatus and then transferred from the client apparatus and received by and retained into the reproduction apparatus can be used.
In such an instance, there is the possibility that, for example, part of a plurality of content data which can be transmitted from the server apparatus may already be retained in the reproduction apparatus. Usually, content data retained already in the reproduction apparatus need not be downloaded from the server apparatus to the reproduction apparatus through the client apparatus again. Therefore, if a function which can distinguish content data retained already in the reproduction apparatus and content data which are not retained in the reproduction apparatus as yet is provided, then the convenience to the user is enhanced. Various techniques for providing such a function as just described have been proposed already, and one of such techniques is disclosed, for example, in Japanese Patent Laid-Open No. 2007-42253.